There are many possible chemical warfare agents that could produce irreversible harm for the exposed persons, but few agents will survive the method of dispersal (shells, grenades, missiles, spray equipment, etc.). Also, attempts to transport chemical warfare agents would likely draw attention from the authorities, particularly since many of these agents are illegal to produce in the U.S. A more likely scenario would involve toxic industrial chemicals, which are in widespread use in the U.S., and are less likely to draw attention. The information below covers the warfare agents, not toxic industrial chemicals.

Nuclear Agents: In a nuclear terrorist event, the hazards are thermal radiation, blast or shock effect, and nuclear radiation. The most protective measure is to be as far away from the blast or burst as possible. For nuclear radiation, both distance and shielding help for the initial radiation, consisting of penetrating gamma and beta radiation. Residual nuclear radiation is commonly referred to as fallout and consists of particles dangerous to inhale or get on the skin. (gamma, alpha, and beta particles).

Biological Agents: There are many different types of possible agents that could cause disease---small pox, anthrax, plague, tularemia, and viral hemorrhagic fever, believed to be among the most likely terrorist agents. All biological terrorist agents cause illness or infection when inhaled and some go through mucous membranes (eyes, mouth, etc.). Also, injection via contaminated needles will cause exposure.

Toxins: Some living organisms (bacteria, fungi, algae, and plants) produce very toxic by-products. Most of these toxins are difficult to produce in large amounts and are sensitive to heat and light, thereby rendering them ineffective as weapons. However, inappropriate use of gene technology together with biotechnology could enhance toxin production and modify the organism's genes to produce toxin less sensitive to breakdown by heat or light. The most poisonous substance known is botulism toxin, produced by Clostridium botulism. A marine algae produces Saxitoxin which is also a very lethal toxin.

Chemical Agents: Chemical agents are often referred to as "gases." This term is not appropriate since chemical warfare agents are rarely "gases." Historically, most chemical warfare agents have been liquids or solids. The reason for the use of liquids or solids is the ease of dispersing these agents over long distances. All cause harm when inhaled and many are absorbed through the skin or cause chemical burns on the skin.

Since the nature of the agent and the resulting exposure level are likely to be unknown, it is important to protect all potential routes of entry--lungs, skin, mucous membranes. That means respiratory protection and full body covering that is resistant to penetration or degradation by these agents.

The best protection is Chemical, Biological, Radiological, and Nuclear (CBRN) resistant full body covering with a NIOSH CBRN approved self-contained breathing apparatus (SCBA) worn inside the suit. The SCBA is basically a cylinder of clean air connected to a facepiece. This type of protection takes considerable knowledge, experience, and training to put on properly and costs many thousands of dollars.

More readily available air purifying respirators (negative pressure cartridge types and positive pressure cartridge versions with blowers) offer some level of protection to the lungs, but above some concentration level, these types of respirators are not protective enough. Furthermore, for negative pressure respirators, the facepiece must be tightly sealed to the face; otherwise the toxic agent will escape around the sealing surface into the breathing area and bypass the cartridge/filters entirely. That means that you need to be fit-tested to verify that the mask fits your face. Negative pressure air purifying respirators also require some training and experience to use properly.

In addition to respiratory protection, one needs full body covering--a CBRN resistant full body suit (with booties) and gloves so that all portions of the skin and mucous membranes are shielded from contact with the agent. This suit will protect against skin absorption and chemical burns and may provide limited shielding from radioactive debris.

The need for treatment and decontamination should be minimized as much as possible by contamination avoidance and early warning. The objective of "shelter-in-place" and personal protective equipment, including respiratory protection, is contamination avoidance. Good community planning for communication in terrorist events should provide early warning. For some agents, there is no effective treatment or antidote available. If someone inhales or ingests an agent or the material gets on his or her skin, the key is to get that person to medical professionals as soon as possible for proper treatment and decontamination.

In the event that trained personnel are not immediately available, there are some recommended decontamination measures that a knowledgeable person may carry out.

If someone does come in contact with a chemical warfare agent, the first step is to remove all clothing from the contaminated person in such a way as to not further spread contamination from the clothing onto the body. Obviously, the person removing the clothing must also protect his hands and skin. A mixture of chlorinated lime and magnesium oxide may be applied to affected area to decompose and absorb the agent on the skin. The affected person should shower shortly afterwards to remove the chlorinated lime, which tends to be irritating to the skin. Hot water and detergents with "perborates" are effective for blister and nerve agents. Talcum powder and flour will absorb the agent, but not necessarily deactivate the agent.